Backing-lined sanitary article and process for the production thereof

ABSTRACT

Sanitary applicances with a casing, such as bath tubs, shower trays or washbasins, are glass fiber- and asbestos-free, and are further characterized in that the reinforcing material is 1.5 to 10 mm thick and consists of one or two layers. The one layer or the first layer of a multilayered reinforcement is obtained by hardening a first polylmerizable, cole-hardenable, reactive (meth)acrylate system sprayed on the back of the acrylic glass moulding. The (meth)acrylate system contains as filler hollow microparticles, preferably made of plastics, filled with an inert gas. The composition of the (meth)acrylate system is defined by the invention. The disclosed sanitary appliances meet all requirements of the DIN EN 19 norm and can be recycled.

The invention relates to backing-lined sanitary articles according tothe precharacterizing clause of claim 1 and to a process for theproduction of such sanitary articles.

In particular, the invention relates to bathtubs or shower trays orsinks, which have a preferably thermoformed acrylic glass mouldingreinforced on its reverse with 1.5 to 10 mm thick polymer material,which is glass fibre- and asbestos-free and is bonded firmly to theacrylic glass moulding without additional adhesion promoters, thisreinforcement being obtainable by polymerization of a (meth)acrylatesystem.

The following publications are mentioned for the closer prior art:

D1=Patent Abstracts of Japan, unexamined applications, section M, volume17, no.694, Dec. 17, 1993, The Patent Office Japanese Government page 45M 1531; & JP-A-05 237 854;

D2=DE 36 44 111 A1;

D3=FR 2 640 909;

D4=EP-A-0 693 503;

D5=EP-A-0 285 046;

D6=EP-A-0 345 581;

Reinforced acrylic glass mouldings as baths or basins in the sanitarysector are known in principle. Thus, Japanese Laid-Open SpecificationJP-A 05-237854 of Mitsubishi Rayon (=D1) describes a production processin which a filler-containing containing resin mixture is introduced intoa gap between the mould and thermoformed acrylic glass moulding and thencured integrally in contact with the moulding. A mixture of 90 parts bywt. of a prepolymer of a methacrylic ester and 10 parts by wt. of amethacrylate monomer with 60 wt. % aluminium hydroxide, for example, isused as the filler-containing resin mixture. This mixture is poured,together with-initiator and crosslinking agent, into a gap 8 mm thickbetween the preformed acrylic glass component and the mould. The mixturein the gap can then be cured for 4 h, the surface of the gap between themould and the moulding being covered with a polyester film.

Fillers which are proposed for the resin mixture to be poured in are, inaddition to aluminium hydroxide, furthermore calcium carbonate, glassfibres or carbon fibres.

Although laminated composite bodies, in particular bathtubs or showertrays or also sinks, which have entirely satisfactory properties inrespect of the adhesion of the reinforcing layer to the thermoformedacrylic glass moulding of the base and in respect of the strength of theentire composite body are obtainable by the casting process proposed inthe Japanese Laid-Open Specification D1 referred to, both the mouldingand the process for its production have particular disadvantages in atleast two respects.

On the one hand, for production of the backing-lined moulding, a secondmould in which the volume required for casting the reinforcingcomposition must also be taken into account is always necessary.

On the other hand, only a relatively thick backing lining of thethermoformed moulding (8 mm in the abovementioned example) is possible,since relatively large differences in thickness can easily occur in acasting process, and these can no longer be tolerated at backing liningthicknesses which are too low, such as would be entirely desirable onthe basis of consumption of material and saving weight.

D2 (=DE 36 44 111 A1) discloses a process for the production of abathtub reinforced with plastic, in which a tub which has been producedfrom acrylic glass by the thermoforming process is reinforced with aglass fibre-reinforced polyester resin layer sprayed onto the outside.However, both the fibre reinforcement and the backing lining withpolyester material are unsuitable for simple and substantially completerecyclability of used mouldings, and indeed render this almostimpossible.

FR 2 640 909 (=D3 ) relates to a sandwich structural component for thesanitary sector of thermoplastic resin (e.g. PMMA), and a glass fibremat preformed on the structural component mould of the thermoplasticresin component. These components are bonded in a mould by injecting ina syrupy polyester formulation between the preformed acrylic and fibrecomponents. The possibility of using an acrylic resin is also mentioned.As in D2, the use of glass fibres, whether in the form of mat or of achopped roving, is to be regarded as prohibitive for reprocessing ofused mouldings. Furthermore, the process suggested by D3 is under nocircumstances a spray process, but rather an injection (squirting)process, which requires just as much outlay and is just asdisadvantageous as the casting process of D1. Several working steps,several people, several moulds and reworking steps are required toarrive at a product.

Reinforced sanitary articles which have a thermoformed acrylic glassmoulding reinforced on its reverse with a layer of a fibre-containingpolymer material which is bonded firmly to the acrylic glass mouldingwithout additional adhesion promoters are also known from EP-A-0 693 503(=D4).

These backing-lined sanitary articles are characterized in that thereinforcing layer is 1 to 5 mm thick and is obtainable by curing apolymerizable, cold-curing, reactive (meth)acrylate system sprayed on tothe reverse of the acrylic glass moulding. The (meth)acrylate systemhere comprises, as essential constituents, in addition to thepolymerizable constituents, a redox system, fine fillers and, forreinforcement, 10-50 per cent by weight of chopped glass fibres.

One advantage of the known backing-lined sanitary article is said to bethat its reprocessing by depolymerization—provided that the fine fillersare accordingly suitably chosen—is said to be possible without problems.Although this applies without limitation in respect of the fine fillerswhich can be seen from D4, the chopped glass fibres required in largequantities for the reinforcement are not unproblematic in thedepolymerization, which unfortunately has been confirmed by extensiveresults from practice. Although it can be assumed in theory that thechopped fibres from used components collect on the surface of the metalbath required for the depolymerization and can be skimmed off with aslide bar or doctor blade, it has been found that the chopped fibresremain in the metal bath to a degree which cannot be ignored, and cannotbe readily separated off. Furthermore, the chopped glass fibres inprinciple are to be evaluated in the same way as asbestos fibres inrespect of work safety. A health hazard to the operating personnel dueto the chopped glass fibres, which are partly obtained in the form ofdust during the depolymerization, cannot readily be excluded. It wouldaccordingly a priori be highly desirable to dispense with such fibrefillers.

In addition, the (meth)acrylate systems on which the reinforcing layersfrom the prior art are based tend at least in some cases towardsdisturbances in curing, for example air inclusions etc. The choppedglass fibres essential for the reinforcement protrude, which means thatafter spraying on, the fibres of some centimetres length do not lie flaton the reverse of the moulding, but during development of the tanglewithin the reinforcing material the fibres can project from the plane ofthe moulding to a greater or lesser degree. Rolling for compensating thedisturbances in curing and pressing on the fibre reinforcements aretherefore unavoidable. This manual reworking—that is to say reworking byhand—requires outlay and makes the product more expensive.

Although the impression could be gained that the production variantdisclosed in D4 could also manage without glass fibre-reinforcement, D4documents the need for glass fibre reinforcements through all theexamples. In addition, component G) according to D4 is designated anessential constituent of the reinforcing layer. However, an essentialconstituent cannot be simply omitted without raising doubts as to thesuccess of the technical doctrine. This is a clear indication that thetechnical doctrine of D4 includes no reinforcing layers which are freefrom glass fibres and therefore discloses and renders accessible nocorresponding solution to the expert. There is therefore still theunsolved problem of backing-lined sanitary articles which are completelyrecyclable and are free from chopped glass fibres and polyester resin,and as a result of course an increased demand for such articles.

D5 and D6 merely disclose the technological background in respect of thesubject of the present Application.

In view of the prior art mentioned herein and discussed in detail, anobject of the invention was to provide reinforced sanitary articleswhich are free from chopped glass fibres and free from asbestos.

The provision of completely recyclable sanitary articles which are basedon acrylic glass mouldings has furthermore been the object of theinvention.

Another object of the invention is to provide completely recyclablebacking-lined acrylic glass mouldings which are completely recyclable asfar as possible without a hazard to the operating personnel, inparticular using the depolymerization technique by means of metal bathswhich is known for acrylic glass.

Another object of the invention is to provide backing-lined sanitaryarticles which, with the maximum possible saving of material, meet thegeneral requirements imposed on sanitary articles in respect ofstability.

It was also an object of the invention here, inter alia, to providesanitary articles with an adequate durability of the reinforcing layeralso, and in particular, without an additional adhesion promoter.

The formation of cracks in the reinforcing layer should also besuppressed as far as possible.

Yet another object is to provide, for acrylic glass mouldings, coatingswhich have the highest possible impact strength.

In particular, the provision of acrylic glass mouldings with thethinnest possible coating and a coating of highest possible impactstrength is an object on which the invention is based.

Furthermore, the new sanitary articles should be as simple as possibleto produce.

Reworking by hand should furthermore be reduced to a minimum.

A process for the production of backing-lined acrylic glass mouldingswhich is as non-hazardous as possible is furthermore to be provided.

Finally, the capability of the highest and simplest possible automationof the process for the production of backing-lined acrylic glassmouldings also plays a not insignificant role.

These objects and further objects which, although not mentionedindividually word-for-word, can be readily inferred from theintroductory discussion of the prior art or can be deduced as a matterof course, are achieved by a backing-lined sanitary article having allthe features of claim 1.

The claims referring to the independent product claim provideadvantageous embodiments of the sanitary article according to theinvention.

From the process respect, the features of claim 8 provide a solution tothe problem on which the invention is based in respect of the processaspects. Advantageous process variants are protected in the processclaims dependent on the independent process claim.

In particular, by the fact that, in a backing-lined sanitary articlecomprising an acrylic glass moulding which is reinforced on its reversewith 1.5 to 10 mm thick polymer material which is free from glass fibresand asbestos and is firmly bonded to the acrylic glass moulding withoutadditional adhesion promoters, the reinforcing material or reinforcementmaterial is obtainable by curing a polymerizable, cold-curing, reactive(meth)acrylate system which is sprayed on to the reverse of the acrylicglass moulding and which comprises

A) a) (meth)acrylate 30-100 wt. % a1) methyl (meth)acrylate 0-100 wt. %a2) C₂-C₄ (meth)acrylate 0-100 wt. % a3) ≧C₅ (meth)acrylate 0-50 wt. %a4) polyfunctional (meth)acrylates 0-50 wt. % b) comonomers 0-50 wt. %b1) vinylaromatics 0-30 wt. % b2) vinyl esters 0-30 wt. %

B) per 1 part by wt. of A), 0.05-5 parts by wt. of a (pre)polymer whichis soluble or swellable in A)

C) a redox system which is to be kept completely or partly separate fromthe constituents of the system which are to be polymerized until thepolymerization and comprises an accelerator and a peroxidic catalyst orinitiator in an amount sufficient for cold-curing of component A)

D) customary additives

E) fillers which are inert under the conditions of 0-75 wt. %depolymerization, based on the sum of A)-E), with a fineness ≦100 μm F)hollow microparticles, preferably of plastic, filled 0.1-50 wt. %, withinert gas, based on the sum of A)-F)

it is possible to meet all the requirements imposed by the standardinstitutes and industrial processors in respect of the physicalproperties of the sanitary article in an outstanding manner and toachieve a large number of further additional advantages.

These include, inter alia:

Complete recyclability by the route of depolymerization known per se,inter alia avoiding polyesters (absence of polyester resin) coupled withavoiding dusts which are unacceptable to health (absence of choppedglass fibres).

Omission of the “rolling step” in the production and as a result moreextensive automation of the production process by spray robots.

Mechanical properties according to DIN EN 198 (deformability, impactstrength, rigidity) are adhered to in an outstanding manner and metbeyond the extent required.

High strength of the mouldings under stress and outstanding durabilityof the bond between the backing-lining layer and acrylic glass moulding.

In contrast to JP-A 05-237854, the process according to the invention isnot an injection process in which the filler-containing resin mixture isintroduced into a gap between the thermoformed acrylic glass mouldingand a mould, but a spray process which requires no mould. A decisiveadvantage of the spray process here is the fact that for different tubdesigns, no correspondingly shaped, expensive moulds are required.

In JP-A 05-237854, the curing time of the mixture in the gap between theacrylic glass moulding and mould is stated as 4 hours. In contrast, thespray system according to the invention cures after 15-25 minutes at ahardener dosage of 5%. This means a substantial shortening of theproduction time.

Due to the preferred absence of solvent from the (meth)acrylate system,the risk of the occurrence of stress cracking is minimized.Solvent-containing systems in particular tend towards stress cracking inthe finished reinforcing layer in the alternating temperature testaccording to DIN EN 198.

Compared with EP-A-0 693 503, there is not only the advantage of absenceof chopped glass fibres or also glass fibre reinforcement generally,which is essential for complete recyclability, it has been found, inparticular, that mechanical deficits still arise in sanitary articlesaccording to EP-A-0 693 503, which raise doubts as to the suitability ofthe articles from EP-A-0 693 503. Thus, by using certain fillers F) inthe reinforcing layer, it is possible to greatly improve precisely themechanical and physical properties of a sanitary article according tothe invention.

A backing-lined sanitary article of the invention comprises an acrylicglass moulding and at least one reinforcing backing-lining layer.

The Acrylic Glass Moulding

The shape and nature of the acrylic glass moulding which isbacking-lined according to the invention are initially not subject toany particular limitation. Mouldings of acrylic glass which have beenproduced by all the processes known to the person skilled in the art forshaping acrylic glass can be backing-lined. These include, inter alia,processing via the viscous state, such as casting, pressing andapplication processes, preferably rotational casting, laminate moulding,compression moulding, transfer moulding, painting, dipping, coating,knife-coating, laminating and the like; processing via the elastoviscousstate, such as kneading, milling, calendering, extruding, injectionmoulding, preferably sandwich injection moulding and RIM processes;processing via the elastoplastic state, such as drawing, stretchmoulding, blow moulding, foaming, preferably cold-forming processes,such as stretch moulding, stretching, draw moulding, thermoforming,vacuum moulding, pultrusion, extrusion blow moulding, injection blowmoulding, injection moulding blow moulding and injection blow shaping;processing via the viscoelastic state, such as welding, sintering, whirlsintering, flame spraying, hot jet spraying and the like; and processingvia the solid state, such as cutting, stamping, forging, sawing,drilling, turning or milling. Thermoforming in all its variations,vacuum forming, vacuum forming without form limitation, vacuum negativeprocesses, drop-forming processes, vacuum stretch-forming processes,thermoforming suction processes and the like, are preferred. Acrylicglass mouldings obtainable by thermoforming are particularly preferredfor the invention.

There is likewise no limitation in respect of the nature of the acrylicglass. All the acrylic glasses available on the market can be used.

The acrylic glass mouldings which are provided, according to theinvention, with a backing-lining layer comprise in respect of theacrylic glass moulding, in addition to customary additives, chieflystructural units which obey the following formula I in respect of theirchemical structure:

wherein

R¹ is C₁₋₆-alkyl, preferably C₁₋₄-alkyl,

R² is H, C₁₋₆-alkyl, preferably H or C₁₋₄-alkyl, very particularlypreferably H or CH₃, and

n is a positive integer greater than 1.

C₁₋₄-alkyl includes linear and branched alkyl radicals having one tofour carbon atoms. Methyl, ethyl, n-propyl, iso-propyl, n-butyl,2-methyl-1-propyl, sec.-butyl and 2-methyl-2-propyl are of interest inparticular.

C₁₋₆-alkyl includes the radicals mentioned for C₁₋₄-alkyl andadditionally radicals having 5 or 6 carbon atoms, such as, preferably,1-pentyl, 2-pentyl, 3-pentyl, 2,2-dimethyl-1-propyl, 3-methyl-1-butyl,3-methyl-2-butyl, 2-methyl-2-butyl, 2-methyl-1-butyl and 1-hexyl.

Examples of compounds which contain the abovementioned structural unitinclude, in addition to others, polymethyl acrylate, polyethyl acrylate,polymethyl methacrylate, polypropyl acrylate, polybutyl acrylate,polypropyl methacrylate, polybutyl methacrylate and copolymers whichcomprise two or more of these types of polymers. The first fourcompounds are preferred in the context of the invention. Polymethylmethacrylate (PMMA) is very particularly preferred.

In addition to the chemical mixtures (random copolymers or also blockcopolymers) which are formed by copolymerization of at least twosubstituted or unsubstituted acrylic acid ester monomers (e.g. methylmethacrylate/n-butyl methacrylate copolymers), acrylic glass mouldingsfrom copolymers which comprise up to 50 wt. % of at least one othervinylically unsaturated monomer which can be copolymerized with at leastone substituted or unsubstituted acrylic acid ester monomer can also beused in the context of the invention.

Examples of these are, inter alia, methyl methacrylate/styrenecopolymers or methyl methacrylate/butyl acrylate/styrene terpolymers.

The comonomers are optional constituents or components which the acrylicglass preferably comprises in a minor amount in the form of copolymerscontaining them. As a rule, they are chosen such that they have noadverse effect on the properties of the acrylic glass to be usedaccording to the invention.

The comonomer or comonomers mentioned can be employed, inter alia, tomodify the properties of the copolymers in a desired manner, for exampleby increasing or improving the flow properties if the copolymer isheated to the melting point in the context of its processing to glass,or for reducing a residual colour in the copolymer or, by using apolyfunctional monomer, to introduce a certain degree of crosslinkinginto the copolymer in this manner.

Monomers which are suitable for this purpose include, inter alia, vinylesters, vinyl chloride, vinylidene chloride, styrene, α-methylstyreneand the various halogen-substituted styrenes, vinyl and isopropenylether and dienes, such as, for example, 1,3-butadiene anddivinylbenzene. The reduction in the colour of the copolymer canparticularly preferably be achieved, for example, by using anelectron-rich monomer, such as, for example, a vinyl ether, vinylacetate, styrene or α-methylstyrene.

Aromatic vinyl monomers, such as, for example, styrene orα-methylstyrene, are particularly preferred among the comonomercompounds mentioned.

Physical mixtures, so-called blends, are also preferred for the acrylicglass mouldings.

It is also to be taken into account here, inter alia, that the term“acrylic glass” indeed in principle is a collective name for organicsynthetic glasses of polymethacrylates, these being produced in the formof slabs, pipes, bars or blocks by bulk or bead polymerization(suspension polymerization) and subsequent extrusion or injectionmoulding.

In the context of the invention, however, by definition all themodifications described herein above are also to be understood under theterm “acrylic glass”.

However, synthetic glasses of polymethacrylic acid methyl esters arealso particularly preferred for the invention.

The Backing-lining Layer(s)

In the sanitary articles according to the invention, e.g. tubs andsinks, by the fact that the reinforcing material can have a relativelysmall thickness in the range from 1.5 to 10 mm, preferably 1.5-<8 mm, itis possible to realize a high saving in weight and material, which isaccompanied by a reduction in piece costs while the strength valuesrequired are adhered to. This savings effect is additionally increasedby the nature of the reinforcing layer, in particular also in respect ofthe fillers F), and the method of application of the materials resultingin the reinforcing layer. An additional savings effect results from thefast curing time.

By using hollow microparticles of plastic filled with inert gas in thebacking-lining layer or layers, it is possible to achieve, in a mannerwhich is not readily foreseeable, a surprising improvement in importantproperties of the reinforced sanitary articles according to theinvention.

The hollow beads which can be employed according to the invention thushave a relatively low density, compared with other very fine fillers, asa result of which the density of the sprayable material is reduced. Thishas the effect of a saving in material of approx. ⅓ for a similar layerthickness.

Furthermore, the mechanical properties of the cured material areimproved considerably. Not only the fact that properties such as theimpact strength or adhesive strength of the composite of acrylic glassmoulding and backing lining are improved at all is surprising here, thequality of the improvement is even much more surprising. Thus,improvements in adhesive strength of 100% and more are to be recorded,compared with reinforcing layers without hollow microbeads.

Finally, the sedimentation properties of the fillers in the cold-curing(meth)acrylate resins are found to be improved dramatically. While withconventional resins demixing problems already have to be combated aftera storage time of a few weeks or even days, the (meth)acrylate resinswith fillers of category F) are still absolutely homogeneous and show nosediment at all even after several weeks, which significantlyfacilitates their processability by the user.

In a very particular embodiment, a sanitary article according to theinvention is characterized in that the reinforcing material comprises afirst and a second layer, the first layer being obtainable by curing apolymerizable, cold-curing, reactive, first (meth)acrylate system whichis sprayed onto the reverse of the acrylic glass moulding and whichcomprises

A) a) (meth)acrylate 30-100 wt. % a1) methyl (meth)acrylate 0-100 wt. %a2) C₂-C₄ (meth)acrylate 0-100 wt. % a3) ≧C₅ (meth)acrylate 10-50 wt. %a4) polyfunctional (meth)acrylates 0-50 wt. % b) comonomers 0-50 wt. %b1) vinylaromatics 0-30 wt. % b2) vinyl esters 0-30 wt. %

B) per 1 part by wt. of A), 0.05-5 parts by wt. of a (pre)polymer whichis soluble or swellable in A)

C) a redox system which is to be kept completely or partly separate fromthe constituents of the system which are to be polymerized until thepolymerization and comprises an accelerator and a peroxidic catalyst orinitiator in an amount sufficient for cold-curing of component A)

D) customary additives

E) very fine fillers which are inert under the conditions ofdepolymerization, based on the sum of A)-E), with a fineness ≦100 μm0-75 wt. %

F) hollow microparticles, preferably of plastic, filled 0.1-50 wt. %,with inert gas, based on the sum of A)-F)

and the second layer being obtainable by curing a polymerizable,cold-curing, reactive, second (meth)acrylate system which is sprayedonto the first layer and differs from the first (meth)acrylate system,the same general definition applying to the second (meth)acrylate systemas to the first (meth)acrylate system, apart from component a3) , i.e.apart from the content of ≧C₅ (meth)acrylate, which is 0 to <10 wt. %,and apart from component F), which is present in an amount of 0-50 wt.%, based on the sum of A)-F).

Although all the requirements of DIN EN 198 can already be met with asingle-layered reinforcement on the basis of the particular fillers, thetwo-layered reinforcement has the advantage, in the context of theinvention, that certain mechanical properties (above all the impactstrength) of the finished sanitary article can be improved further.

The backing-lining or reinforcing layer, like the minimum of twobacking-lining layers which reinforce the acrylic glass moulding in anexpedient modification of the invention, are obtainable by curing one orby curing two or more polymerizable, cold-curing, reactive(meth)acrylate systems, each of which are composed of components A) toD), which together represent the binder, as well as the fillers E) andF).

This means in a first variant that one (meth)acrylate system forms thesole reinforcing layer on the reverse of a sanitary article of mouldedacrylic glass.

This also means that in a second variant a first (meth)acrylate systemforms a first layer on the reverse of the acrylic glass moulding, whilea second (meth)acrylate system forms a second layer on the reverse ofthe acrylic glass moulding and the first layer on the reverse.

Although in the latter case both, that is to say both the first and thesecond (meth)acrylate system can comprise components A) to F), theindividual constituents are chosen in respect of nature and/or amountfrom the definitions stated such that the first and second(meth)acrylate system differ clearly from one another.

The Binder

The binder of a (meth)acrylate system is in turn composed ofpolymerizable monomers A), optionally (pre)polymers B) which are solubleor swellable in this, a redox system C) and, optionally, furthercustomary additives D).

Component A

Component A) is an essential constituent of the binder and therefore ofthe reinforcing layer.

First Variant: Only One Reinforcing Layer

A single monomer, e.g. methyl methacrylate, can be employed as monomerA), but a mixture is usually used. The composition of component A) is:

(meth)acrylate 30-100 wt. % methyl (meth)acrylate 0-100 wt. % C₂-C₄(meth)acrylate 0-100 wt. % ≧C₅ (meth)acrylate 0-50 wt. % polyfunctional(meth)acrylates 0-50 wt. % comonomers 0-50 wt. % vinylaromatics 0-30 wt.% vinyl esters 0-30 wt. %

Styrene is preferably limited to max. 20 wt. % in A), since a highercontent leads to disturbances in the cold-curing and severe odournuisances are to be expected.

A constituent in parentheses represents optional use thereof, i.e.(meth)acrylate represents acrylate and/or methacrylate.

Monomer component A) comprises at least 30 wt. % (meth)acrylate,monofunctional (meth)acrylates with a C₁-C₄-ester radical beingpreferred. Longer-chain esters, i.e. those with a C₅- or longer-chainester radical, are limited to 50 wt. % in component A).

The long-chain (meth)acrylates in the amount stated make the system moreimpact-resistant. These esters therefore indeed make the backing liningof the acrylic glass mouldings more flexible, but also softer, as aresult of which the use properties would be limited with amounts above50 wt.%. Component A) preferably also comprises polyfunctional(meth)acrylates. In the first case, the ≧C₅ (meth)acrylates arepreferably contained in the (meth)acrylate system in component A) in anamount of 10-30 wt. %, particularly expediently in an amount of 15-25wt. %.

In addition to the (meth)acrylates, component A) can also comprise othercomonomers, the proportion thereof being limited to 50 wt. %. Amongthese comonomers, component A) can comprise vinylaromatics and/or vinylesters to the extent in each case of up to 30 wt. %. Higher proportionsof vinylaromatics are difficult to polymerize in and can lead to ademixing of the system. Higher proportions of vinyl esters canfurthermore cure completely only inadequately at low temperatures andtend towards greater shrinkage properties.

Component A) is preferably built up to the extent of 80-100 wt. %, andparticularly preferably to the extent of 90-100 wt. %, from(meth)acrylates, since favourable processing and use properties for thebacking lining can be achieved with these monomers. The proportion ofC₂-C₄-esters in (meth)acrylates is preferably limited to 50 wt. % incomponent A), and component A) preferably comprises these esters to theextent of max. 30 wt. %, and particularly advantageously to the extentof max. 20 wt. %. Particularly flexible backing-lining layers can bebuilt up by this means.

Suitable monofunctional (meth)acrylates are, in particular, methylmethacrylate, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate,ethyl triglycol methacrylate and hydroxypropyl methacrylate.

Particularly suitable comonomers are vinyltoluene, styrene and vinylesters.

Component A) particularly advantageously comprises polyfunctional(meth)acrylates, the content thereof in A) usually being in the rangefrom 1 to 50 wt. %, and in most cases 1 to 10 wt. %. The polyfunctional(meth)acrylates are used for polymer linkage between linear molecules.Properties such as flexibility, scratch resistance, glass transitiontemperature, melting point or curing processes can be influenced as aresult.

Polyfunctional (meth)acrylates which can be employed include, interalia:

(i) Difunctional (meth)acrylates

Compounds of the general formula:

wherein R is hydrogen or methyl and n . . . [sic] a positive integerbetween 3 and 20, such as e.g. the di(meth)acrylate of propanediol,butanediol, hexanediol, octanediol, nonanediol, decanediol andeicosanediol, compounds of the general formula:

wherein R is hydrogen or methyl and n . . . [sic] a positive integerbetween 1 and 14, such as e.g. the di(meth)acrylate of ethylene glycol,diethylene glycol, triethylene glycol, tetraethylene glycol,dodecaethylene glycol, tetradecaethylene glycol, propylene glycol,dipropylene glycol and tetradecapropylene glycol; and glyceroldi(meth)acrylate,2,2′-bis[p-(γ-methacryloxy-β-hydroxypropoxy)-phenylpropane] or bis-GMA,bisphenol A dimethacrylate, neopentylglycol di(meth)acrylate,2,2′-di(4-methacryloxypolyethoxyphenyl)propane having 2 to 10 ethoxygroups per molecule and 1,2-bis(3-methacryloxy-2-hydroxypropoxy)butane.

(ii) Tri- or polyfunctional (meth)acrylates

Trimethylolpropane tri(meth)acrylate and pentaerythritoltetra(meth)acrylate.

Preferred conventional polyfunctional (meth)acrylates include, inaddition to others, triethylene glycol dimethacrylate (TEDMA),trimethylolpropane trimethacrylate (TRIM), 1,4-butanediol dimethacrylate(1,4-BDMA) and ethylene glycol dimethacrylate (EDMA).

Second Variant: at Least Two Reinforcing Layers

a)first (meth)acrylate system, i.e. methacrylate system of the firstreinforcing layer, i.e. that reinforcing layer which is sprayed directlyon to the acrylic glass moulding and cured thereon.

The composition of component A) for this case is:

(meth)acrylate 30-100 wt. % methyl (meth)acrylate 0-100 wt. % C₂-C₄(meth)acrylate 0-100 wt. % ≧C₅ (meth)acrylate 10-50 wt. % polyfunctional(meth)acrylates 0-50 wt. % comonomers 0-50 wt. % vinylaromatics 0-30 wt.% vinyl esters 0-30 wt. %

Longer-chain (meth)acrylates, i.e. those with a C₅- or longer-chainester radical, are an essential constituent in the (meth)acrylates ofthe first (meth)acrylate system, since they make up at least 10 wt. % ofthe (meth)acrylates and therefore also of component A) of the first(meth)acrylate system.

b)second (meth)acrylate system, i.e. (meth)acrylate system of the secondreinforcing layer, i.e. that layer which is sprayed on to a firstreinforcing layer already sprayed on to the reverse of the acrylic glassmoulding and is cured on the first reinforcing layer.

The same general definition applies to the second (meth)acrylate system,in respect of the nature of the monomers (component A)), as forcomponent A) of the first (meth)acrylate system, there being asubstantial difference in the ≧C₅-methacrylates.

The composition of component A) is:

(meth)acrylate 30-100 wt. % methyl (meth)acrylate 0-100 wt. % C₂-C₄(meth)acrylate 0-100 wt. % ≧C₅ (meth)acrylate 0-<10 wt. % polyfunctional(meth)acrylates 0-50 wt. % comonomers 0-50 wt. % vinylaromatics 0-30 wt.% vinyl esters 0-30 wt. %

Longer-chain esters, i.e. those with a C₅- or longer-chain esterradical, are limited to <10 wt. % in component A). These esters indeedmake the backing lining of the acrylic glass mouldings more flexible,but also softer, which means that their use properties are limited. As aresult, the formulation of the second layer (small proportion of≧C₅-esters) is harder and therefore more rigid compared with the firstlayer.

Component B)

The following description applies both to a single-layered reinforcementand to the first and also the second (meth)acrylate system of amultilayered reinforcement, and if several reinforcing layers arepresent the particular component B) in each of the systems obeys thefollowing definition independently of one another.

Component B) is essential.

To establish the viscosity of the binder and the overall rheology of thesystem and the better complete curing, a polymer or prepolymer B) isadded to component A). This (pre)polymer should be soluble or swellablein A). 0.05 to 5 parts of prepolymer B) are employed per one part of A).Poly(meth)acrylates are particularly suitable, it being possible forthese to be dissolved as a solid polymer in A), or it being possible fora so-called syrup, i.e. partly polymerized compositions of correspondingmonomers, to be employed. Polyvinyl chloride, polyvinyl acetate,polystyrene, epoxy resins, epoxy (meth)acrylates, unsaturatedpolyesters, polyurethanes or mixtures thereof are furthermore suitable.These polymers have the effect in the binder of e.g. specificflexibility properties or shrinkage regulation and act as a stabilizer,skin-forming agent or flow improver.

The backing-lining layers preferably comprise 10-30 wt. %, particularlyadvantageously 15-20 wt. %, of a high molecular weight polymer B), e.g.poly(meth)acrylate, based on the sum of A)+B).

In a preferred embodiment, the weight ratio of components B) and A) ofthe binder is in the range from 0.1:1 to 2:1. An optimum match isachieved by this means.

Weight ratios of B):A) in the range from 0.2:1 to 1:1 are particularlyexpedient.

Component B) ((pre)polymer) can be a suspension polymer, emulsionpolymer and/or grinding granules from recycling processes. The averageparticle diameter of the prepolymers is then usually <0.8 mm.

Prepolymer B) is very advantageously a PMMA paint bead obtainable bysuspension polymerization. This also allows, in particular,single-layered reinforcements of adequate impact strength.

The average particle diameter of the paint bead here is about 0.1-0.8mm. 0.2-0.8 mm is preferred, in particular 0.4-0.8 mm.

The following description of component B) of the binder and therefore ofa reinforcing layer applies in particular to the embodiment with atleast two reinforcing layers.

(Pre)polymer B) is preferably a copolymer, it being possible for thehardness and flexibility of the reinforcing layers to be influenced bythe nature and amount of the comonomer in (pre)polymer B). Comonomerswhich can be employed and which participate in the build-up of theparticular (pre)polymer B) include, inter alia, acrylates andmethacrylates other than methyl methacrylate (MMA), vinyl esters, vinylchloride, vinylidene chloride, styrene, α-methylstyrene and the varioushalogen-substituted styrenes, vinyl and isopropenyl ether and dienes,such as, for example, 1,3-butadiene and divinylbenzene.

Preferred comonomers for methyl methacrylate are, inter alia. ethylacrylate, butyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate,n-butyl methacrylate, 1-butyl methacrylate, 2-ethylhexy methacrylate,propyl acrylate, propyl methacrylate, methacrylic acid, ethyl triglycolmethacrylate and hydroxypropyl methacrylate.

The comonomer content of prepolymers B) for the first reinforcing layeris favourably 30-80%, and for the second reinforcing layer is favourably0-<30%, in each case based on the total weight of the monomers ormonomer units participating in the build-up of a prepolymer B).

Component C)

Component C) is an essential component of the binder and therefore ofeach reinforcing layer.

The following description applies both to a single-layered reinforcementand to the first and also the second (meth)acrylate system of amultilayered reinforcement, component C) in each of the systems obeyingthe definition independently of one another.

The binder (A) to D)) to be used according to the invention in the(meth)acrylate system is in each case suitable for cold-curing, i.e.comprises, for the polymerization, a redox system of an accelerator anda peroxidic catalyst or initiator, these components being added in asufficient amount for cold-curing of component A).

It goes without saying that either the redox system or at leastcomponents thereof are to be kept separate from the polymerizablesubstances of the binder until the desired time of the polymerization.

The accelerator is usually employed in A) to D) in an amount of 0.01 to5 wt. %, particularly advantageously to the extent of 0.5 to 1.5 wt. %.

Particularly suitable accelerators are amines and mercaptans, anddimethyl-p-toluidine, diisopropoxy-p-toluidine, diethylol-p-toluidine[sic], dimethylaniline and glycol dimercaptoacetate are preferred.Organic metal salts furthermore serve as accelerators, and are usuallyemployed in A) to D) in the range from 0.001 to 2 wt. %. Suitable saltsare e.g. cobalt naphthenate, copper naphthenate, cobalt oleate andcopper oleate.

Dibenzoyl peroxide and dilauroyl peroxide are particularly suitable asthe peroxidic catalyst. The peroxides are usually employed in the binderto the extent of 0.1 to 10 wt. %, and in particular to the extent of 0.5to 5 wt. %. An aqueous 40% suspension of stabilized dibenzoyl peroxide(e.g. Cadox 40 E from Akzo) is expediently employed as the peroxidiccatalyst for the spray resin system.

The binder can already comprise the accelerator, e.g.dimethylparatoluidine, of component C), without polymerization takingplace at ambient temperature. The reaction is started by addition of theremaining constituents of component C), the amount of component C)usually being chosen such that the (meth)acrylate system has a pot lifein the range from 10 min to 30 min.

The (meth)acrylate system according to the invention thus comprises thecomplete component C) only immediately before use, and until use itcomprises none or only part of component C).

Solvent-free hardener components are very particularly preferablyemployed.

Component D)

The following description applies both to a single-layered reinforcementand to the first and also the second (meth)acrylate system of amultilayered reinforcement, component D) in each of the systems obeyingthe definition independently of one another.

Component D) is an optional component.

The binder (A) to D)) can furthermore also comprise conventionaladditives D) such as are usually employed in reactive (meth)acrylatesystems. These additives serve e.g. to increase the oxygen inhibition,and for this paraffins to the extent of 0.05 to 5 wt. % in the binder(A) to D)) and/or phosphites to the extent of 0.01 to 1 wt. % in A) toD) and also a polymer skin formation (paraffin-free) are particularlysuitable. For the latter, in order to achieve a non-inhibited surfacewithout paraffins, e.g. extremely high molecular weight polymers areused as additives, in particular in the case of the sole use of methylmethacrylate. Methyl methacrylate already evaporates at the surfaceduring curing and leaves behind a non-tacky surface by polymer skinformation.

Defoamers, wetting agents, thixotropic agents, inhibitors, mattingagents, bluing agents, UV stabilizers and polymerization chainregulators can furthermore be added.

Of these, thixotropic agents are particularly preferred. These serve toimprove the storage stability and the sedimentation properties ofparticles in the resin components.

In a preferred embodiment, the backing-lined sanitary article of theinvention is characterized in that at least one of the resin systemsused for the backing lining comprises up to 0.5 part of thixotropicagent part per 1 part of particles E), based on the fillers E).

Conventional thixotropic agents are e.g. silica, e.g. Aerosil®200 andAerosil®300.

The Fillers

The fillers of a (meth)acrylate system of the invention are composed oftypes E) and F). Type E) is optional, while fillers F) are essential atleast for one of the reinforcements according to the invention.

Component E)

The following description applies both to a single-layered reinforcementand to the first and also the second (meth)acrylate system of amultilayered reinforcement, component E) in each of the systems obeyingthe definition independently of one another.

The single as well as the first and also the second (meth)acrylatesystem comprise component E) as optional constituents, that is to sayone or more filler(s) which is/are inert under the conditions ofdepolymerization of the (meth)acrylates and has/have a fineness of ≦100μm, in an amount of up to 0-75 wt. %, based on the sum of A) to E). Itgoes without saying here that the first (meth)acrylate system cancomprise different fillers to the second, that is to say that the natureand amount of the fillers are independent of one another in theframework stated.

In respect of the invention, fillers here which are inert under theconditions of depolymerization of the (meth)acrylates are to beunderstood as meaning those substances which do not substantiallyadversely influence or even render impossible depolymerization ofacrylate polymers.

Acrylate polymers, above all PMMA, are among the few plastics which areoutstandingly suitable for direct chemical recycling. This is to beunderstood as meaning that these polymers can be broken down againcompletely into the corresponding monomer units (depolymerization) atcertain temperatures and pressures if heat is supplied in a suitablemanner. Thus, for example, various continuous and discontinuousprocedures are described in the literature and in patent specificationsfor depolymerization of polymethyl methacrylate (PMMA) and recovery ofthe monomeric methyl methacrylate (MMA) obtained as a result by heattreatment of acrylic glass waste at temperatures >200° C., condensationof the monomer vapours formed and working up of the crude monomers. Inthe process which is used most frequently in industry, the polymermaterial is introduced into a tank, which is partly filled with lead andis heated externally. The polymer material depolymerizes at temperaturesabove 400° C. and the monomer vapours formed pass via a pipeline to acondenser where they are condensed to a crude, liquid monomer.Corresponding depolymerization processes are known, for example, fromDE-OS 21 32 716.

Fillers E) such as are now employed in the context of the inventionshould not be substances or, in the course of the depolymerization,result in decomposition products which render impossible or makeunnecessarily difficult working up of the crude liquid monomer which isto be recycled in the depolymerization. Those fillers which collect asslag on the surface of the metal and, for example, can be removed with arake, slide bar or the like during operation of the reactor aretherefore preferred. A backing-lined sanitary article which iscompletely recyclable therefore exists by using fillers E) according tothe invention.

Mineral fillers are usually used as the fillers. The fillers which canadvantageously be employed in a single or in the first and/or second(meth)acrylate system include, in the context of the invention, mica,aluminium hydroxide, calcitic fillers, such as, for example, chalk andmarble, quartzitic fillers, such as wollastonite, cristobalite and thelike, amorphous silicates, flue ash, silicon carbide and/or barite.

Of these, mica, aluminium trihydrate (aluminium hydroxide) andquartzitic and calcitic fillers are particularly suitable for theinvention. The use of mica both in the first and second (meth)acrylatesystem or also in the (meth)acrylate system of a single-layeredreinforcement is extremely advantageous.

Fillers E) are used either by themselves or in a combination of several.As already stated, the amount is between 0 and 75 wt. %, based on thesum of components A) to E) of the binder+fillers.

If the proportion of fillers E) is higher than 75 wt. %, this canadversely influence the mixing and processing properties of thebacking-lining material, in particular a mixture with such a highproportion of filler can be sprayed or pumped only poorly. Furthermore,at higher filler contents it can no longer be ensured that sufficientbinder is available to obtain a stable coating.

On the other hand, a relatively high proportion of fillers E) ispreferred according to the invention. The highest possible amount issought in particular for cost reasons. Fillers E) are preferablycontained in an amount of 40-65 wt. %, particularly preferably in anamount of 50-60 wt. %, in each case based on the sum of componentsA)-E).

Smooth fillers are preferred for the invention. By this is to beunderstood particles which have the smoothest possible surfaces. Theparticle size of the fillers according to the invention is ≦100 μm. Theyare consequently very fine fillers. The particle size of fillers E) isdetermined by sieve analysis and is necessary in the stated size inorder to ensure processing of the fillers E)+binders A)-D) system. Inprocessing by spraying in particular, the size of the filler particlesis limited by the nozzle system used. However, the size of the fillerparticles E) is to be adapted to the requirements of the processingsystem by the person skilled in the art.

Furthermore, small-filler particles with a smooth surface are coatedbetter by binders, tend less towards aggregation, and do not form aircushions in the reinforcing layer.

In a particular modification, a backing-lined sanitary article of theinvention is therefore characterized in that the fillers E) of the first(meth)acrylate system, which cures to give a first layer on the reverse,have a fineness of ≦30 mm. Very fine fillers of this type allow aparticularly clean and easy curing of the first layer and problem-freeapplication of the second layer.

Component F)

First Variant: Single-layered Reinforcement

The following description initially relates to the case of asingle-layered reinforcement.

Filler component F) is essential to the invention for a single-layeredreinforcement. The microparticles F) are an essential component of asingle-layered reinforcement.

A whole range of microparticles can be employed for the reinforcinglayer according to the invention. In principle, these are hollowparticles, which can be regular or irregular, but which are preferablyball-shaped or spherical and contain an inert gas in their hollowcavity.

The hollow microbeads which can be used as component F) in principleinclude hollow microbeads of various materials, such as e.g. glass,metals, metal oxides, polymers and organic compounds.

Hollow microbeads of plastic are preferably employed for the invention.

Hollow microbeads which are particularly preferably employed ascomponent F) for the reinforcing layer in the present invention arethose which are made of polymers, such as e.g. polystyrene, polyvinylchloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate,polyacrylonitrile, polybutadiene and polyethylene terephthalate; andfurthermore hollow microbeads of copolymers or terpolymers which arebased on those monomers which form the copolymers mentioned are alsopreferred.

Examples of such polymers and copolymers which are the hollow beadsthemselves are, inter alia, vinylidene chloride/acrylonitrile copolymer,polyvinylidene chloride, acrylonitrile/vinylidene chloride copolymer,acrylonitrile/methacrylonitrile copolymer,acrylonitrile/divinylbenzene/vinylidene chloride copolymer and the like.

Mixtures of hollow microbeads can also preferably be employed ascomponent F) in the context of the invention.

The hollow microbeads or the microparticles which can be employedaccording to the invention can be coated with coatings to adapt theprocessing properties or to vary the reinforcing properties.

Modifications of the simple hollow microbeads are also particularlysuitable. For example, those hollow microbeads which are made ofpolymers which are covered (coated) with mineral substances in order toensure a better stability towards the influence of the ambient medium(acrylate resin) are of particular interest.

The coating of the hollow microbeads can comprise very fine-grainedminerals, such as e.g. calcium carbonate, quartz, mica, aluminiumhydroxide, cristobalite and the like.

Hollow microbeads, in particular those of plastic, coated with calciumcarbonate are particularly preferred.

The hollow microbeads which have a particularly favourable action ascomponent F) in the context of the invention can in principle beproduced, as well as by other methods, in the following manner:

Coating of a core (sacrifice core) with the material in question, thecore is then removed by various methods (e.g. dissolving in a solvent,evaporation or volatilization), so that only the shell remains. Hollowmicrobeads are produced above all from ceramic materials and metaloxides by this method.

Production in a nozzle reactor (nozzle reactor system):

In this case, the gas in the hollow microbeads and the liquefiedmaterial for the shell of the beads are sprayed via speciallyconstructed nozzle systems (concentric openings). The liquefied materialcools in a type of spray tower and solidifies to a hollow microbeadfilled with the particular gas (e.g. H₂O, CO₂, SO₂, air, N₂, etc.).Hollow microbeads are produced above all from polymeric materials bythis method.

Phase separation of emulsions by liquid extraction: In this case, thespherical, liquid-filled particles (micelles) present in an emulsion areseparated off from the surrounding liquid and then dried. Hollowmicrobeads are produced above all from metal oxides, but also frompolymers, by this method.

A review of the production of hollow microbeads is to be found, forexample, in Mat. Res. Soc. Symp. Proc. Vol. 372, 1995 Materials ResearchSociety by David L. Wilcox, Sr. and Morris Berg, pages 3 to 13, and theliterature cited therein.

Particularly suitable types of gas-filled hollow microbeads of plasticinclude, inter alia, ®Dualite types, e.g. ®Dualite M 6017AE, (Pierce &Stevens Corp.); ®Expancel types, e.g. ®Expancel 642 WU, ®Ropaque types,e.g. ®Ropaque OP 62 (Rohm & Haas Co.), Matsumoto Microspheres, e.g.Microsphere F-30E (Matsumoto Yushi Seiyaku Co. Ltd.) and the like.

The amount of fillers F) in the or a reinforcing layer according to theinvention is in general critical. If the proportion of hollow microbeadsF) is below 0.1 wt. %, based on the sum of all the constituents of the(meth)acrylate system, the effects according to the invention do notemerge in a sufficiently pronounced manner, in particular the physicalproperties are not improved sufficiently. Use of the microparticles,which are preferably made of plastic, in an amount of more than 50 wt.%, based on the sum of A)-F), is in general not advisable, since it doesnot seem possible to achieve an effect in respect of improving thephysical properties of the reinforcing layer which bears a relationshipto the additional cost outlay.

In a particular embodiment of the sanitary article according to theinvention, this comprises filler F) in the (meth)acrylate system or inthe first and/or second (meth)acrylate system in an amount in the rangefrom 1 to 25 wt. %, based on the weight of the sum of constituentsA)-F).

It is furthermore particularly advantageous if the sanitary articlecomprises filler F) in the (meth)acrylate system or in the first and/orsecond (meth)acrylate system in an amount in the range from 2 to 15 wt.%, based on the weight of the sum of constituents A)-F).

In another preferred embodiment, the sanitary article according to theinvention is characterized in that filler F) is contained in the(meth)acrylate system or in the first and/or second (meth)acrylatesystem in an amount in the range from 3 to 10 wt. %, based on the weightof the sum of constituents A)-F).

Second Variant: Two- or Multilayered Reinforcement

In principle, that which has been stated for the single-layered variantapplies in respect of the nature of filler F). It is important that two-or multilayered backing linings according to the invention comprisehollow microbeads F) in at least one layer. However, each individuallayer can also accordingly comprise these hollow microbeads. Theparticles F) are preferably in the first backing-lining layer, i.e. thatlayer which is applied directly to the acrylic glass moulding as thefirst layer.

By simple experiments, the expert can choose the constituents, withinthe limits stated, according to nature and amount such that he obtains asingle-layered backing lining which complies with DIN EN 198 or, in thecase of a two-layered backing lining, a first backing-lining layer whichgives the sanitary article the required impact strength, and such thathe obtains a second backing-lining layer which imparts to the sanitaryarticle the necessary rigidity.

The total reinforcement is usually 1.5 to 10 mm thick. Two layerstogether are as a rule likewise about 1.5 to 10 mm thick. It isadvantageous here to form the first layer thinner and the second layerthicker than the first layer.

The second layer is advantageously about 2 to 3× as thick as the first.The total reinforcement in all cases is advantageously 1.5 to <8 mmthick.

Expediently, the first layer has a thickness in the range of 0.5-2.5 mmand the second layer has a thickness in the range of 3-<5.5 mm.

It was particularly astonishing here that with a single- or two-layeredbacking lining according to the invention, it was possible to producesufficiently reinforced sanitary articles without glass fibrereinforcement.

The chopped glass fibres in the finished backing-lining layer accordingto the prior art usually form a tangle.

This felting effect has hitherto been regarded as unavoidable in orderto obtain a reinforcement of adequate mechanical strength. The inventionis to be evaluated as all the more surprising.

The present invention also provides a process for the production of abacking-lined sanitary article which is free from glass fibres andasbestos, in which a reactive resin system is sprayed onto the reverseof a moulding of acrylic glass, the resin system curing in contact withthe acrylic glass moulding and during this procedure bonding to theacrylic glass moulding, the process being characterized in that a resinsystem which is based chiefly on (meth)acrylates, cures to a polymerhaving a glass transition temperature Tg>70° C. and comprises, based on1 part by wt. of the resin system, up to 2.33 parts by wt. of thosefillers which are inert under the conditions of depolymerization of theacrylic glass moulding is used, the resin system having the compositionstated herein.

The process is preferably carried out in a manner in which two resinsystems which differ from one another and are based chiefly on(meth)acrylates are used in succession, which systems each cure to apolymer having a glass transition temperature Tg>70° C. and cancomprise, based on 1 part by wt. of the resin system, up to 2.33 partsby wt. of those fillers which are inert under the conditions ofdepolymerization of the acrylic glass moulding, a first resin systemwhich imparts the required impact strength initially being sprayed ontothe acrylic glass moulding and, after curing thereof, a second resinsystem which imparts the necessary rigidity being sprayed thereon. It isknown from EP-A-0 693 503 to apply a resin system based on(meth)acrylates by the spray process. Analogously thereto, in apreferred variant according to the invention, two layers are applied insuccession, attention additionally being paid in the choice of thepossible fillers to their harmlessness in the depolymerization of thepolymers, a one hundred per cent recyclable product, which at the sametime can be produced in a manner which particularly saves material andis simple in the sequence of the spray process, being accessible bycareful matching of the choice of material (both the moulding and thebacking lining are based on (meth)acrylates and the fillers are inert)and the application process of the backing-lining layers.

Furthermore, and above all, glass fibres are avoided in all layers,whether in one or in both or several.

The process of the invention is preferably distinguished in that apolymerizable, cold-curing, reactive (meth)acrylate system whichcomprises

A) a) (meth)acrylate 30-100 wt. % a1) methyl (meth)acrylate 0-100 wt. %a2) C₂-C₄ (meth)acrylate 0-100 wt. % a3) ≧C₅ (meth)acrylate 10-50 wt. %a4) polyfunctional (meth)acrylates 0-50 wt. % b) comonomers 0-50 wt. %b1) vinylaromatics 0-30 wt. % b2) vinyl esters 0-30 wt. %

B) per 1 part of A), 0.05-5 parts of a (pre)polymer which is soluble orswellable in A)

C) a redox system which is to be kept completely or partly separate fromthe polymerizable constituents of the system until the polymerizationand comprises an accelerator and a peroxidic catalyst or initiator in anamount sufficient for cold-curing of component A)

D) customary additives

E) fillers, based on the sum of A)-E) 0-75 wt. %,

 the fillers having a particle size of ≦100 μm

F) hollow microparticles, preferably of plastic, filled 0.1-50 wt. %,with inert gas, based on the sum of A)-F)

is used as the first resin system.

It is furthermore preferable that a polymerizable, cold-curing, reactive(meth)acrylate system which comprises

A) a) (meth)acrylate 30-100 wt. % a1) methyl (meth)acrylate 0-100 wt. %a2) C₂-C₄ (meth)acrylate 0-100 wt. % a3) ≧C_(5 (meth)acrylate) 0-<10 wt.% a4) polyfunctional (meth)acrylates 0-50 wt. % b) comonomers 0-50 wt. %b1) vinylaromatics 0-30 wt. % b2) vinyl esters 0-30 wt. %

B) per 1 part of A), 0.05-5 parts of a (pre)polymer which is soluble orswellable in A)

C) a redox system which is to be kept completely or partly separate fromthe polymerizable constituents of the system until the polymerizationand comprises an accelerator and a peroxidic catalyst or initiator in anamount sufficient for cold-curing of component A)

D) customary additives

E) fillers, based on the sum of A)-E 0-75 wt. %, the fillers having aparticle size <100 μm F) hollow microparticles, preferably of plastic,0.1-50 wt. %, filled with inert gas, based on the sum of A)-F)

 the fillers having a particle size <100 μm

F) hollow microparticles, preferably of plastic, filled with inert gas,based on the sum of A)-F) 0.1-50 wt. %,

is used as the second resin system.

To improve the sedimentation properties of fillers E) during relativelylong storage times before use and therefore to increase the storagestability, it is preferable, before use of the reactive resin system, toincorporate fillers E) into the first and/or second system of bindersA)-D) with a homogenizing unit with the addition of a thixotropic agentin an amount of 0.1-0.5 parts, based on 1 part of E).

By using a suitable homogenizing unit in the preparation of the resinsystem, the size and shape of the filler particles are furthermoreinfluenced in a positive manner.

The backing-lined sanitary articles according to the invention can beproduced successively by spraying or squirting a resin system A) to F)or the particular resin systems A) to F) onto the reverse of the acrylicglass moulding.

In this procedure, two streams of material are in each case preferablymixed with one another during the spraying, a first of the streams ofmaterial comprising the polymerizable constituents of the resin mixtureand a second stream of material comprising the constituents of componentC) of the resin system which are to be kept separate from thepolymerizable constituents of the resin system until the polymerization.

High-pressure airless spray units (e.g. Aplicator [sic] IP 8000 fromESSKA, Hamburg), surface jet spray units from Glascraft or atwo-component metering and mixing unit with an operating pressure of 40to 60 bar (e.g. “Twin-Injection” from Reinhardt Technik Kierspe) arepreferably used for the spraying-on. Using such units, especially in thefan jet process, coatings can be applied with a simultaneous significantreduction in the emission values. This can advantageously be achievedwith spray guns which allow individual regulation of the loss-freelaminate application.

Particularly suitable mixing and atomizing processes are provided by EP38 481.

The process of the invention is particularly distinguished in that itcan be carried out at ambient temperature, i.e. usually between 0 and35° C., but also, if desired, at more extreme temperatures, such as −10to +45° C.

The invention is explained in more detail below with the aid ofembodiment examples, with reference to the attached figure.

COMPARISON EXAMPLE 1

(VB1)

Single-layered reinforcement without hollow microbeads, approx. 3 mmthick

40.00 parts by wt. of a binder comprising

18.00% polymethyl methacrylate 75.00% methyl methacrylate 5.00%triethylene glycol dimethacrylate 0.50% paraffins (melting point <56°C.) 0.50% dimethylparatoluidine 0.50% diisopropoxyparatoluidine 0.50%additives, stabilizers

are stirred with

60.00 parts by wt. mica (<100 μm) and 0.10 part by wt. thixotropic agent(Byk 410)

for 4 hours.

The mixture has a viscosity of 11,000-13,000 mPas.

This mixture is applied with a high-pressure airless spray unit of thetype Applicator IP 8000 together with Cadox 40 E in a volume ratio of100:2 to 100:5, under a spray pressure of 180 bar, on to the mouldedacrylic glass component. The amount applied is 6-7 kg/m². Manualreworking is not necessary. A backing-lining layer about 3 mm thick isobtained.

At a hardener dosage of 100:2, the curing time is about 15-25 min.

At a hardener dosage of 100:4, the curing time is about 5-15 min.

COMPARISON EXAMPLE 2

(VB2)

Two-layered reinforcement with reinforcing layer 1 a, but both layerswithout hollow microbeads, joint thickness of the two layers togetherabout 6 mm;

(i) Reinforcing Layer 1 a

40.00 parts by wt. of a binder comprising

30.00% polymethyl methacrylate 42.00% methyl methacrylate 25.70%2-ethylhexyl acrylate 0.50% triethylene glycol dimethacrylate 0.80%diisopropylolparatoluidine [sic] 0.70% dimethylparatoluidine 0.30%paraffin (melting point <56° C.)

are stirred with

60.00 parts by wt. calcium carbonate (<100 μm) and 0.10 part by wt.thixotropic agent (Byk 410)

for 4 hours.

The mixture has a viscosity of 6,000-10,000 mPas.

This mixture is applied with a high-pressure airless spray unit of thetype Applicator IP 8000 together with Cadox 40 E in a volume ratio of100:2 to 100:5, under a spray pressure of 180 bar, on to the mouldedacrylic glass component. Manual reworking is not necessary. The amountapplied is 2-4 kg/m².

At a hardener dosage of 100:2, the curing time is 15-40 min.

At a hardener dosage of 100:5, the curing time is 5-20 min.

A second spray application is then carried out with the followingmixture:

(ii) Reinforcing Layer 1

40.00 parts by wt. of a binder comprising

18.00% polymethyl methacrylate 75.00% methyl methacrylate 5.00%triethylene glycol dimethacrylate 0.50% paraffins (melting point <56°C.) 0.50% dimethylparatoluidine 0.50% diisopropylolparatoluidine [sic]0.50% additives, stabilizers

are stirred with

60.00 parts by wt. mica (<100 μm) 0.10 part by wt. thixotropic agent(Byk 410)

for 4 hours.

The mixture has a viscosity of 11,000-13,000 mPas.

The hardener dosage is 100:2 to 100:5.

The spray pressure is. 180 bar.

The amount applied is 6-10 kg/m².

The curing time is 15-30 min at a hardener dosage of 100:2.

At a hardener dosage of 100:5, the curing time is about 5-15 min.

EXAMPLE 3

(B3)

Single-layered reinforcement with hollow microbeads, thickness of thebacking-lining layer approx. 3 mm;

40.00 parts by wt. of a binder comprising

18.00% polymethyl methacrylate 75.00% methyl methacrylate 5.00%triethylene glycol dimethacrylate 0.50% paraffins (melting point <56°C.) 0.50% dimethylparatoluidine 0.50% diisopropoxyparatoluidine 0.50%additives, stabilizers

are stirred with

54.00 parts by wt. mica (<100 μm) 6.00 parts by wt. gas-filled hollowmicrobeads of acrylonitrile copolymer, coated with calcium carbonate andhaving an average particle size of about 95 μm, of the type ® Dualite6032 from Pierce & Stevens Corporation and 0.10 part by wt. thixotropicagent (Byk 410)

for 4 hours.

The mixture has a viscosity of 11,000-13,000 mPas.

This mixture is applied with a high-pressure airless spray unit of thetype Applicator IP 8000 together with Cadox 40 E in a volume ratio of100:2 to 100:5, under a spray pressure of 180 bar, to the mouldedacrylic glass component. The amount applied is about 4-7 kg/M². Manualreworking is not necessary. A backing-lining layer about 3 mm thick isobtained.

At a hardener dosage of 100:2, the curing time is about 15-25 min.

At a hardener dosage of 100:4, the curing time is about 5-15 min.

EXAMPLE 4

(B4)

Two-layered reinforcement with reinforcing layer 1 a, first reinforcinglayer 1 a with hollow microbeads, second reinforcing layer withouthollow microbeads, thickness of each reinforcing layer about 1.5 mm,thickness of the total reinforcement about 3 mm;

(i) Reinforcing Layer 1 a

40.00 parts by wt. of a binder comprising

30.00% polymethyl methacrylate 42.00% methyl methacrylate 25.70%2-ethylhexyl acrylate 0.50% triethylene glycol dimethacrylate 0.80%diisopropylolparatoluidine [sic] 0.70% dimethylparatoluidine 0.30%paraffins (melting point <56° C.)

are stirred with

54.00 parts by wt. mica (<100 μm) 6.00 parts by wt. gas-filled hollowmicrobeads of acrylonitrile copolymer, coated with calcium carbonate andhaving an average particle size of about 95 μm, of the type ® Dualite6032 from Pierce & Stevens Corporation and 0.10 part by wt. thixotropicagent (Byk 410)

or 4 hours.

The mixture has a viscosity of 6,000-10,000 mpas.

This mixture is applied with a high-pressure airless spray unit of thetype Applicator IP 8000 together with Cadox 40 E in a volume ratio of100:2 to 100:5, under a spray pressure of 180 bar, to the mouldedacrylic glass component. Manual reworking is not necessary. The amountapplied is about 2-3.5 kg/m².

At a hardener dosage of 100:2, the curing time is 15-40 min.

At a hardener dosage of 100:5, the curing time is 5-20 min.

A second spray application is then carried out with the followingmixture:

(ii) Reinforcing Layer 1

40.00 parts by wt. of a binder comprising

18.00% polymethyl methacrylate 75.00% methyl methacrylate 5.00%triethylene glycol dimethacrylate 0.50% paraffins (melting point <56°C.) 0.50% dimethylparatoluidine 0.50% diisopropylolparatoluidine [sic]0.50% additives, stabilizers

are stirred with

60.00 parts by wt. mica (<100 μm) 0.10 part by wt. thixotropic agent(Byk 410)

for 4 hours.

The mixture has a viscosity of 11,000-13,000 mPas.

The hardener dosage is 100:2 to 100:5.

The spray pressure is 180 bar.

The amount applied is 2-3.5 kg/m².

The curing time is 15-30 min at a hardener dosage of 100:2.

At a hardener dosage of 100:5, the curing time is about 5-15 min.

After the curing, the complete tubs are subjected to tests according toDIN EN 198, and the testing bodies which are cut out of the finishedtubs, are subjected to tests according to DIN ISO 4624 DIN ISO 178 andDIN ISO 179. The specifications from the provisions applicable in eachcase in 1996 were used.

In the testing by the hot water alternating test according to DIN EN198, a tub is filled alternately with water of 75° C. and then of 12° C.DIN EN 198 requires 100 such cycles to be survived without damage.Survival means that the state of the tube shows no detachment of thereinforcement and no cracks in the acrylic glass.

The behaviour under impact stress in accordance with the falling balltest according to DIN EN 198 is acceptable if no damage to the surfaceand the underneath of a tub occurs after a steel ball of 200 g falls onto the base of the tub from a height of 1 m.

These and the other results can be seen from table 1.

TABLE 1 Hot water alternating Falling Impact Adhesive Flexural test ballExample/ strength strength strength DIN EN test com- DIN ISO DIN ISO DINISO 198 DIN EN parison 179 4624 178 Number of 198 example kJ/m² N/mm²MPa cycles Damage VB1  8 0.3 15 150 none (defective) VB2 10 — — 200 none(defective) B3 25 0.5 25 350 none (intact) B4 15 0.5 20 210 none(defective)

What is claimed is:
 1. A backing-lined sanitary article comprising anacrylic glass molding having a finished side and an opposite reverseside, which is reinforced on its reverse side with 1.5 to 10 mm thickpolymer material that is free from glass fibers and asbestos and isbonded to the acrylic glass molding without additional adhesionpromoters, wherein the reinforcing material comprises a first and asecond layer, the first layer obtained by curing a polymerizable,cold-curing, reactive first (meth)acrylate system that is sprayed ontothe reverse side of the acrylic glass molding and which comprises A) a)a (meth)acrylate component, in an amount of 50-100 wt. %, which consistsof a1) methyl (meth)acrylate, in an amount of 0-100 wt. %, a2) C₂-C₄(meth)acrylate, in an amount of 0-100 wt. %; a3)≧C₅ (meth)acrylate, inan amount of 10-50 wt. %, and a4) polyfunctional (meth)acrylatesselected from the group consisting of di-, tri-, and tetra-functional(meth)acrylates, in an amount of 0-50 wt. % b) a comonomer component, inan amount of 0-50 wt. %, which consists of b1) vinylaromatics, in anamount of 0-30 wt. %, and b2) vinyl esters, in an amount of 0-30 wt. %,wherein all weight percents are based on the total weight of the monomercomponent A), B) a (pre)polymer, which is soluble or swellable in themonomer component A), in an amount of 0.05-5 parts by weight per 1 partby weight of A), C) a redox system, which is to be kept separate fromthe constituents of the system to be polymerized until thepolymerization, and which comprises an accelerator, and a periodiccatalyst or initiator, in an amount sufficient for cold-curing ofcomponent A), D) customary additives, E) fine fillers, which are inertunder the conditions of depolymerization of acrylic polymers, includingheat treatment at a temperature greater than 200° F., and which have aparticle diameter of ≦100 μm, in an amount of 0-75 wt. %, based on thesum of A)-E), and F) hollow microparticles filled with inert gas, in anamount of 0.1-50 wt. %, based on the sum of A)-F), the second layerobtained by curing a polymerizable, cold-curing, reactive second(meth)acrylate system that is sprayed onto the first layer and whichcomprises A) a) a (meth)acrylate component, in an amount of 50-100 wt.%, which consists of a1) methyl (meth)acrylate, in an amount of 0-100wt. %, a2) C₂-C₄ (meth)acrylate, in an amount of 0-100 wt. %, a3)≧C₅(meth)acrylate, in an amount of 0-<10 wt. %, and a4) polyfunctional(meth)acrylates selected from the group consisting of di-, tri-, andtetra functional (meth)acrylates, in an amount of 0-50 wt. %, b) acomonomer component, in an amount of 0-50 wt. %, which consists of b1)vinylaromatics, in an amount of 0-30 wt. %, and b2) vinyl esters, in anamount of 0-30 wt. %, wherein all weight percents are based on the totalweight of the monomer component A), B) a (pre)polymer, which is solubleor swellable in the monomer component A), in an amount of 0.05-5 partsby weight per 1 part by weight of A), C) a redox system, which is to bekept separate from the constituents of the system to be polymerizeduntil the polymerization, and which comprises an accelerator, and aperiodic catalyst or initiator, in an amount sufficient for cold-curingof component A), D) customary additives, E) fine fillers, which areinert under the conditions of depolymerization of acrylic polymers,including heat treatment at a temperature greater than 200° F., andwhich have a particle diameter of ≧100 μm, in an amount of 0-75 wt. %,based on the sum of A)-E), and F) hollow microparticles filled withinert gas, in an amount of 0-50 wt. %, based in the sum of A)-F).
 2. Thesanitary article according to claim 1, wherein filler F) in the firstand second (meth)acrylate systems comprises gas-filled, expanded hollowmicrobeads of plastic.
 3. The sanitary article according to claim 2,wherein the hollow microbeads are coated with calcium carbonate.
 4. Thesanitary article according to claim 1, wherein filler E) in the firstand second (meth)acrylate systems is mica.
 5. The sanitary articleaccording to claim 1, wherein the first and second (meth)acrylatesystems have a weight ratio of components B) A) in the range of 0.1:1 to2:1.
 6. The sanitary article according to claim 5, wherein the weightratio of components B):A) is in the range of 0.2:1 to 1:1.
 7. Thesanitary article according to claim 1, wherein the first layer has athickness of 0.5-2.5 mm, and the second layer has a thickness in therange of 2.5-<5.5 mm.
 8. A process for the production of thebacking-lined sanitary article of claim 1, which comprises the steps of:spraying the polymerizable, cold-curing, reactive first (meth)acrylatesystem onto the reverse side of the acrylic glass molding, curing thefirst (meth)acrylate system and allowing it to bond to the acrylic glassmolding to form the first layer, which imparts impact strength, sprayingthe polymerizable, cold-curing, reactive second (meth)acrylate systemonto the first layer, curing the second (meth)acrylate system andallowing it to bond to the first layer to form the second layer, whichimparts rigidity, wherein the first and second (meth)acrylate systemseach comprise fillers E) and microparticles F) in an amount of up to2.33 parts by weight based on 1 part by weight of the particular resinsystem, and wherein the first and second (meth)acrylate systems eachcure to form a polymer having a glass transition temperature Tg>70° C.9. The process according to claim 8, wherein before use of the reactiveresin systems, the filler E) is incorporated into the first and second(meth)acrylate systems with a homogenizing unit with the addition of athixotropic agent in an amount of 0.01-0.5 parts by weight based on 1part by weight of E).
 10. The process according to claim 8, wherein thefiller E) comprises calcium carbonates, chalk, marble, barite,quartzites, wollastonite, cristobalite, amorphous silicates, flue ash,mica, or combinations thereof.
 11. The process according to claim 10,wherein the filler E) comprises mica.
 12. The process according to claim8, wherein the resins systems are sprayed successively onto the reverseside of the acrylic glass molding, during spraying, in each case, twostreams of material are mixed with one another, the first stream ofmaterial comprising the polymerizable constituents of the resin mixtureand the second stream of material comprising the constituents ofcomponent C) of the resin system, which are to be kept separate from thepolymerizable constituents of the resin system until the polymerization.13. The sanitary article according to claim 1, wherein the pre-polymermaterial of at least one of the first and second reinforcing layers is amaterial selected from the group consisting of PMMA paint beads obtainedby suspension polymerization having an average particle diameter of upto 0.8 mm, emulsion polymers, and grinding granules obtained fromrecycling processes.